Rating on Garmin Edge 520 Plus (preloaded basemap (Garmin)).

From the Garmin models currently on sale I would recommend this one as the best buy.

If you don't need the touchscreen then no need to get the Edge 820 - this works brilliantly! I'm very happy and would definitely recommend it. No wifi but the bluetooth upload is very quick (3-5 secs) and routing+mapping is the same as the expensive models!If you need the stated 15 hours of battery life then this only works doing recording but no routing - if you have the map on and following a route then I would estimate you get 5-6 hours (but this is no different to the more expensive models).Route calculation is indeed slow - likely 3 mins for a 100km route... but this doesn't really disturb me as I always know where to go for the first part anyway - and you can just start recording and then then immediately set off while it's still calculating the route. I found re-calculating when you deviate fine at 5-10 sec in the cases I had.If you need 15 hours you need to turn light down, backlight to 15 sec (minimum), glonass off, bluetooth off, beeping off - but then you will also get your 15 hours! And when doing larger breaks then just pause and then power it completely off - you can resume when powering on again.